The field of the invention relates generally to inductors for use in electrical equipment, and more specifically to inductors that include a cast coil and a fringe shield.
Inductors, also referred to as reactors in some applications, may be used in connection with dynamoelectric machines. For example, an inductor may be used in a variable speed wind turbine. A wind turbine uses the wind to generate electricity. A wind turbine typically includes a nacelle that houses an electric generator. The wind turbine also typically includes a rotor that includes a plurality of rotor blades attached to a rotating hub. The rotor is coupled to the electric generator, wherein the wind turbine rotor converts wind energy into rotational energy that is used to rotate the rotor of the electric generator. Variable speed operation of the wind turbine facilitates enhanced capture of energy by the turbine when compared to a constant speed operation of the turbine. However, variable speed operation of the wind turbine produces electricity having varying voltage and/or frequency. More specifically, the frequency of the electricity generated by the variable speed wind turbine is proportional to the speed of rotation of the rotor. A power converter may be coupled between the electric generator and a utility grid. The power converter outputs a fixed voltage and frequency electricity for delivery on the utility grid.
Some known power converters include semiconductor switches capable of handling high currents and voltages. However, the semiconductor switches may not be able to operate at high frequencies due to thermal limitations. To overcome the thermal limitations, a filter may be coupled to the output of the semiconductor switches to filter harmonic content from the electricity. Such filtering adds to the cost, and may adversely impact the efficiency of the power converters.
A power converter that includes multiple threads may facilitate high power and/or high frequency power conditioning without a filter, by producing a low level of harmonic content. In some examples, a power converter that includes multiple threads is coupled to multiple inductors, for example, differential mode inductors and/or common mode inductors. A power converter of this type facilitates cost-savings by eliminating the need for the filter.